Field of the Invention
The present invention relates to an image processing apparatus, a radiation imaging apparatus, an image processing method, and a storage medium.
Description of the Related Art
In recent years, a radiation imaging apparatus that two-dimensionally arranges image sensors (detection units) made of amorphous silicon or single-crystal silicon and captures a radiation image has been put into practical use. In such a radiation imaging apparatus, as processing for reducing the influence of fixed pattern noise caused by the dark current and the like of the image sensors, dark correction processing of subtracting a dark image obtained in a state without radiation irradiation from an object image is performed.
Japanese Patent Laid-Open No. 2004-201784 proposes a technique of correcting the output of an image sensor, which has varied due to the influence of an increase/decrease in a dark current caused by a variation in the operating temperature or an image lag that occurs when capturing an object, based on fixed pattern noise (the fixed output component of the detection unit) obtained from the average value of dark images captured at a predetermined interval.
However, the technique of Japanese Patent Laid-Open No. 2004-201784 corrects the fixed pattern noise (the fixed output component of the detection unit) using the average value of dark images. For this reason, if the timing of obtaining a dark image at a predetermined interval is located after the previous object image capturing, an image lag that may occur in accordance with an input signal affects the correction result. For example, in correction processing, if the fixed output is estimated to be high due to an image lag, overcorrection may occur, and object information may be lost by the correction processing.
The present invention has been made in consideration of the above-described problem, and provides an image processing technique capable of correcting a varying dark component generated by an image lag in dark correction processing.